Thousands of deer in Oklahoma, Missouri, South Dakota, Nebraska and other nearby states have been found dead as a result of either blue tongue disease (BT) or epizootic hemorrhagic disease (EHD), two very similar diseases.

The hot summer of record-breaking temperatures may be part of the reason why so many deer are affected this year. The virus that causes both diseases is transmitted to various ruminants and ungulates by midges, a type of biting fly. Otherwise, it is non-contagious. Deer may be contracting the disease in larger numbers because they are forced to congregate at limited water sources where midges live.

Numerous deer carcasses found in the wild have some wildlife departments withholding the sale of unsold licenses in heavy-hit counties and deer hunting units. BT has already killed a few hundred deer nationwide, while EHD has taken at least a few thousand.

Deer with BT lose their appetite, become emaciated, lose their fear of man and grow progressively weaker. Internal hemorrhaging is present. They tend to salivate more, develop a high fever, drink excessively or lie in water to cool down. The tongue becomes swollen, cyanotic (bluish) and often protrudes from the mouth. Lesions on the foot can also appear.

No warnings against eating meat from infected deer have been issued by the Center for Disease Control and Prevention nor by state wildlife departments. Oklahoma State University Extension Wildlife Specialist Dwayne Elmore told Deer and Deer Hunting, “hunters are at no risk from eating meat from infected animals unless secondary bacterial infections are present.” However, hunters are asked to have their state wildlife department scientists inspect the meat whether it is to be processed or kept as a trophy.

Mortality rates for BT are typically less than 25 percent, but may be higher in some cases. There is nothing humans can do to stop the spread of the virus, but the year’s first frost should be enough to kill the flies that carry the virus. Once a deer with BT dies, the virus dies within 24 hours.